U.S. patent application number 17/163331 was filed with the patent office on 2021-05-20 for transformer resonant converter.
The applicant listed for this patent is Eagle Harbor Technologies, Inc.. Invention is credited to John G. Carscadden, Alex Patrick Henson, Kenneth E. Miller, James R. Prager, Ilia Slobodov, Timothy M. Ziemba.
Application Number | 20210152163 17/163331 |
Document ID | / |
Family ID | 1000005374110 |
Filed Date | 2021-05-20 |
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United States Patent
Application |
20210152163 |
Kind Code |
A1 |
Miller; Kenneth E. ; et
al. |
May 20, 2021 |
TRANSFORMER RESONANT CONVERTER
Abstract
Some embodiments may include a nanosecond pulser comprising a
plurality of solid state switches; a transformer having a stray
inductance, L.sub.s, a stray capacitance, C.sub.s, and a turn ratio
n; and a resistor with a resistance, R, in series between the
transformer and the switches. In some embodiments, the resonant
circuit produces a Q factor according to Q = 1 R L s C s ;
##EQU00001## and the nanosecond pulser produces an output voltage
V.sub.out from an input voltage V.sub.in, according to
V.sub.out=QnV.sub.in.
Inventors: |
Miller; Kenneth E.;
(Seattle, WA) ; Prager; James R.; (Seattle,
WA) ; Ziemba; Timothy M.; (Bainbridge Island, WA)
; Carscadden; John G.; (Seattle, WA) ; Slobodov;
Ilia; (Seattle, WA) ; Henson; Alex Patrick;
(Seattle, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eagle Harbor Technologies, Inc. |
Seattle |
WA |
US |
|
|
Family ID: |
1000005374110 |
Appl. No.: |
17/163331 |
Filed: |
January 29, 2021 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H03K 17/005 20130101;
H03K 17/56 20130101; H03K 3/57 20130101 |
International
Class: |
H03K 3/57 20060101
H03K003/57; H03K 17/00 20060101 H03K017/00; H03K 17/56 20060101
H03K017/56 |
Claims
1. A resonant converter circuit comprising: a DC input providing an
input voltage V.sub.in; a plurality of solid state switches
electrically coupled with the DC input; a transformer comprising: a
transformer core, a primary side comprising a conductive sheet
wrapped at least around a portion of the transformer core, the
conductive sheet electrically coupled with the plurality of solid
state switches; a secondary side comprising a plurality of
secondary windings wrapped at least around a portion of the
transformer core, a stray inductance, L.sub.s, a stray capacitance,
C.sub.s, and a turn ratio, n; a resistor with a resistance, R,
disposed in series between the conductive sheet of the transformer
and the plurality of solid state switches; a plurality of rectifier
diodes coupled with the plurality of secondary windings; and a
circuit output coupled with the plurality of rectifier diodes;
wherein the resonant converter circuit produces a Q factor
according to Q = 1 R L s C s ; ##EQU00006## and wherein the
resonant converter circuit produces output pulses at the circuit
output with an output voltage V.sub.out from the input voltage
V.sub.in, according to V.sub.out=QnV.sub.in.
2. The resonant converter circuit according to claim 1, wherein the
output pulses have a voltage greater than about 10 kV.
3. The resonant converter circuit according to claim 1, wherein the
output pulses have a frequency greater than 25 kHz.
4. The resonant converter circuit according to claim 1, wherein a
resonant frequency is greater than 100 kHz.
5. The resonant converter circuit according to claim 1, wherein the
output pulses have an output power greater than 5 kW.
6. The resonant converter circuit according to claim 1, wherein the
output pulses have an output power greater than 50 kW.
7. The resonant converter circuit according to claim 1, wherein the
resonant converter circuit has a switching transition time less
than 40 ns.
8. The resonant converter circuit according to claim 1, wherein the
resonant converter circuit has a total circuit inductance less than
about 300 nH as measured on a primary side of the transformer.
9. The resonant converter circuit according to claim 1, wherein the
resonant converter circuit operates with a total circuit
capacitance of less than about 100 pF as measured on a secondary
side of the transformer.
10. The resonant converter circuit according to claim 1, wherein
the output pulses have a rise time, with a voltage slew rate
greater than 10.sup.9 V/s.
11. The resonant converter circuit according to claim 1, wherein
the resonant converter circuit has a power density greater than 1
W/cm.sup.3.
12. The resonant converter circuit according to claim 1, wherein
the stray capacitance C.sub.s comprises more than 50% of a total
circuit resonant capacitance C.
13. A resonant converter circuit comprising: a transformer having:
a transformer core; a conductive sheet wrapped at least around a
portion of the transformer core; a plurality of secondary windings
wrapped at least around a portion of the transformer core; a stray
inductance, L.sub.s, wherein the stray inductance, L.sub.s, is not
from an inductor; a stray capacitance, C.sub.s, wherein the stray
capacitance, C.sub.s, is not from a capacitor; and a resistor with
a resistance, R, in series with the transformer; wherein the
resonant converter circuit produces a Q factor according to Q = 1 R
L s C s . ##EQU00007##
14. The resonant converter circuit according to claim 13, wherein
the transformer has a turn ratio n and the resonant converter
circuit produces an output voltage, V.sub.out, from an input
voltage V.sub.in, according to V.sub.out=QnV.sub.in.
15. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit produces a pulse with a voltage
greater than about 10 kV.
16. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit operates at a resonant frequency
greater than 0.1 MHz.
17. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit produces pulses with a switching
transition time less than 40 ns.
18. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit has a total circuit inductance less
than about 300 nH as measured on a primary side of the
transformer.
19. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit operates with a total circuit
capacitance less than about 100 pF as measured on a secondary side
of the transformer.
20. The resonant converter circuit according to claim 13, wherein
the output pulses have a rise time, with a voltage slew rate
greater than 10.sup.9 V/s.
21. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit produces output pulses with a power
density greater than 1 W/cm.sup.3.
22. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit does not include an inductor.
23. The resonant converter circuit according to claim 13, wherein
the resonant converter circuit does not include a capacitor.
24. The resonant converter circuit according to claim 13, wherein a
ratio between a peak output power and an average output power is
greater than a factor of 10.
25. The resonant converter circuit according to claim 13, wherein
the stray inductance L.sub.s comprises more than 50% of a total
circuit inductance.
26. The resonant converter circuit according to claim 13, wherein
output pulses have a rise time with a voltage slew rate greater
than 10.sup.9 V/s.
Description
BACKGROUND
[0001] Producing high voltage pulses with fast rise times is
challenging. For instance, to achieve a fast rise time (e.g., less
than about 50 ns) for a high voltage pulse (e.g., greater than
about 10 kV), the slope of the pulse rise must be incredibly steep.
Such a steep rise time is very difficult to produce. This is
especially difficult using standard electrical components in a
compact manner. It is additionally difficult to produce such a high
voltage pulse with fast rise times having variable pulse widths
and/or a variable high pulse repetition rate.
SUMMARY
[0002] Systems and methods are disclosed for producing high
voltage, high frequency pulses using a switching voltage source and
a transformer that includes a resonant converter such as, for
example, a series resonant converter.
[0003] Some embodiments may include a resonant converter comprising
a DC input, a plurality of solid state switches (which for us might
be comprised of the SPA, a switching power amplifier based on the
full bridge topology); a transformer having a stray inductance,
L.sub.s, a stray capacitance, C.sub.s, and a primary to secondary
turns ratio n; a total series resistance, R, that will be comprised
of the stray series circuit resistance, R.sub.s, and any additional
series resistance, R.sub.a, that is intentionally added to control
Q; a diode rectifier on the secondary side of the transformer; and
an output waveform filter. In some embodiments, the resonant
circuit has a Q factor according to
Q = 1 R L s C s ; ##EQU00002##
and the resonant converter produces an output voltage V.sub.out
from an input voltage V.sub.in, according to V.sub.out=QnV.sub.in.
In some embodiments, the stray inductance is measured from the
primary side of the transformer and the stray capacitance is
measured from the secondary side. In some embodiments, additional
capacitance, C.sub.a, and/or inductance, L.sub.a, may be included
to produce a desired resonant frequency and/or change the circuit
Q.
[0004] Some embodiments may include a resonant converter circuit
having a transformer having a stray inductance, L.sub.s, and a
stray capacitance, C.sub.s; and a stray resistance with a
resistance, R.sub.s, in series with the transformer. In some
embodiments, the resonant circuit produces a Q factor according
to
Q = 1 R L C , ##EQU00003##
where R is the sum of the series stray resistance R.sub.s and any
additionally added resistance R.sub.a and equivalent series load
resistance R.sub.L, C is the sum of the stray capacitance C.sub.s
and any added capacitance C.sub.a and any other stray capacitance
C.sub.so, and L is the sum of the stray series inductance L.sub.s
and any additional added inductance L.sub.a and any other stray
series inductance L.sub.so.
[0005] In some embodiments, the output can have a voltage greater
than 5 kV, 15 kV, and/or 50 kV.
[0006] In some embodiments, the resonant converter can operate with
a frequency greater than about 25 kHz or 100 kHz.
[0007] In some embodiments, the ratio between a peak output power
and an average output power is greater than a factor of 10.
[0008] In some embodiments, the stray inductance L.sub.s comprises
more than 50% of the total circuit inductance.
[0009] In some embodiments, the output pulses have a rise time with
a voltage slew rate greater than 10.sup.9 V/s.
[0010] In some embodiments, the resonant converter includes an
output that is galvanically isolated from its input (e.g., a
floating output).
[0011] In some embodiments, the pulse output voltage can be
adjusted during the pulse duration with a timescale of less than 10
.mu.s to make the adjustment to a new voltage output level.
[0012] In some embodiments, the stray capacitance C.sub.s comprises
more than 50% of the total circuit resonant capacitance.
[0013] In some embodiments, the peak output power is greater than 5
kW or greater than 50 kW.
[0014] The embodiments described in this document, whether in the
summary or elsewhere, are mentioned not to limit or define the
disclosure, but to provide examples to aid understanding thereof.
Additional embodiments are discussed in the Detailed Description,
and further description is provided there. Advantages offered by
one or more of the various embodiments may be further understood by
examining this specification or by practicing one or more
embodiments presented.
BRIEF DESCRIPTION OF THE FIGURES
[0015] FIG. 1 is an example transformer resonant converter
according to some embodiments.
[0016] FIG. 2 is a circuit diagram of an example transformer
resonant converter coupled with switching circuitry and a load
according to some embodiments.
[0017] FIG. 3 is a photograph of an example resonant converter.
[0018] FIG. 4 is an example waveform created from a transformer
resonant converter according to some embodiments.
[0019] FIG. 5 is an example waveform created from a transformer
resonant converter according to some embodiments.
[0020] FIG. 6 is an idealized example of a series resonant circuit
according to some embodiments.
[0021] FIG. 7 is a circuit diagram of an example transformer
resonant converter according to some embodiments.
DETAILED DESCRIPTION
[0022] Systems and methods are disclosed for producing high
voltage, high frequency pulses using a switching voltage source and
a transformer, arranged with other components, to be a series
resonant converter, or a transformer resonant converter. The
switching voltage source, for example, may include a full bridge or
a half bridge topology. For example, the switching voltage source
may include a full bridge or a half bridge switch topology. As
another example, the switching voltage source may have additional
output filter elements. The switching voltage source, for example,
may include a full bridge topology or a half bridge topology. In
some embodiments, the switching voltage source may include a
switching power amplifier.
[0023] The transformer resonant converter, for example, may not
include any physical capacitors and/or inductors. Instead, in some
embodiments, the transformer resonant converter may include a
resistor in series with the stray capacitance and/or the stray
inductance of at least the transformer. The stray inductance,
L.sub.so, and/or stray capacitance, C.sub.so, of other circuit
elements may also be leveraged as part of the resonant converter.
In some embodiments, the total stray inductance and/or the stray
capacitance can be small. For example, the stray inductance can be
less than about 3,000 nH, 300 nH, 30 nH, 3 nH etc., as measured on
the primary side of the transformer. As another example, the stray
capacitance can be less than about 300 pF or less than about 30 pF,
as measured on the secondary side of the transformer. Additional
capacitance, C.sub.a, and inductance, L.sub.a, may be added in
conjunction such as, for example, in parallel and/or series with
the stray capacitance and stray inductance.
[0024] Resonant converters typically leverage the resonance of a
circuit when the circuit is driven at the resonant frequency (an
example series resonant circuit is shown in FIG. 6). The resonant
frequency can be determined from the total inductance and
capacitance of the circuit elements, for example, from the
following:
f = 1 2 .pi. L C ( 1 ) ##EQU00004##
in this example, L and C represent the total effective and/or
equivalent series circuit inductance and capacitance, respectively,
and as defined above, L=L.sub.s+L.sub.so+L.sub.a, and
C=Cs+C.sub.so+C.sub.a. FIG. 6 shows an idealized series resonant
circuit 600 without any resistance; and with an inductor 620, a
capacitor 610, and power source 605. Resistance may be present in
various forms throughout the circuit.
[0025] When a resonant circuit is driven at its resonant frequency
the effective reactance of each of the circuit components are equal
in magnitude but opposite in sign. Therefore, they cancel each
other out and all that's left is the real resistance of the circuit
whether composed of stray resistance and/or resistive elements,
including the load. In some cases, this real resistance can be the
resistance of the copper traces and/or any other circuit components
in series with the resonant LC components. The ratio of the
reactive components to the real resistance is defined as the Q
factor, which is a dimensionless parameter that is a good estimate
for what multiplier the driving voltage will ring up to when
measured across either L or C. The resonant frequency and Q factor
can be calculated from the following:
Q = 1 R L C . ( 2 ) ##EQU00005##
R is the total equivalent series/dissipative resistance and may
include any series stray resistance Rs as well as any additionally
added resistance Ra, and additional equivalent series load
resistance R.sub.L, as well as any other dielectric or other
dissipative losses from switches or other components. Typical
resonant converters use discrete physical circuit components for
the inductor, capacitor, and/or a resistor to create a desired Q
factor and resonant frequency f. In some embodiments, additional
resistance may be left out to improve circuit efficiency. In some
embodiments, some form of feedback and control may be used to
regulate the output voltage to a value lower than that which would
naturally be set by the circuit Q. One such form of feedback and
control, for example, may rely on pulse width modulation of the
switching voltage source.
[0026] FIG. 1 is a circuit diagram of an example transformer
resonant converter 100 according to some embodiments. On the
primary side 160 of the transformer, the resonant converter 100 may
include, for example, a DC input 105 coupled with a switch 110. In
some embodiments, the switch may include a freewheeling diode or a
body diode. The switch 110 may open and close at high frequencies,
such as, for example, at the resonant frequency of the transformer
resonant converter 100.
[0027] The switch 110, for example, may be any type of solid-state
switch. The primary side 160 of the resonant converter may also
include resonant series inductance 115 and resonant series
resistance 120. The switch 110, for example, can produce high
frequency pulses such as at frequencies greater than 50 KHz, 500
kHz, 5000 KHz, for example.
[0028] In some embodiments, the switch 110 may operate with
transition times less than, for example, about 40 ns, 10 ns, or 1
ns.
[0029] In some embodiments, the switch 110 may include a
solid-state switch. The switch 100, for example, may include an
IGBT switch, MOSFET switch, FET switch, GaN switch, etc. In some
embodiments, the switch 110 may be a high efficiency switch. In
some embodiments, the switch 110 may be a fast switch (e.g.,
switching with a frequency greater than 100 kHz), which may allow
for an output with low ripple. In some embodiments, pulse width
modulation (PWM) techniques can be utilized for fast control of the
output voltage, to allow, for example, the control of beam
characteristics with tens of .mu.s resolution, for example, when
driving neutral beams.
[0030] The resonant series inductance 115 may include, for example,
stray inductance of the transformer, stray inductance of the
primary side 160 circuitry, and/or a physical inductor. The
resonant series inductance 115 may be small, for example, less than
about 3,000 nH, 300 nH, 30 nH, 3 nH, etc.
[0031] The resonant series resistance 120 may include stray
resistance and/or a physical resistor. In some embodiments, a
physical resistor may lower circuit efficiency, however, a physical
resistor may allow for faster circuit response times, and/or may
reduce the need for feedback and control loops to control/regulate
the output voltage.
[0032] The transformer 125 may include any type of transformer such
as, for example, a toroid shaped transformer with one or more
primary side windings and a plurality of secondary side windings.
As another example, the transformer 125 may be a coaxial
transformer with one or more primary side windings and a plurality
of secondary side windings. In some embodiments, the one or more
primary side windings may include a conductive sheet. In some
embodiments, the one or more secondary windings may include a
conductive sheet.
[0033] The circuitry on the secondary side of the transformer 125
may include resonant series capacitance 130. The resonant series
capacitance 125, for example, may include stray capacitance of the
transformer and/or stray capacitance of the secondary side
circuitry and/or a capacitor. The resonant series capacitance 125
may be small, for example, less than about 1,000 pF, 100 pF, 10 pF,
etc. The resonant series capacitance 125 may be in parallel with
the transformer output. The secondary side 165 of the circuit may
include a rectifier 135 and/or an output filter 140.
[0034] In some embodiments, a primary winding and/or a secondary
winding may include single conductive sheet that is wrapped around
at least a portion of a transformer core. A conductive sheet may
wrap around the outside, top, and inside surfaces of a transformer
core. Conductive traces and/or planes on and/or within the circuit
board may complete the primary turn, and/or connect the primary
turn to other circuit elements. In some embodiments, the conductive
sheet may comprise a metal sheet. In some embodiments, the
conductive sheet may comprise sections of pipe, tube, and/or other
thin walled metal objects that have a certain geometry.
[0035] In some embodiments, a conductive sheet may terminate on one
or more pads on a circuit board. In some embodiments, a conductive
sheet may terminate with two or more wires.
[0036] In some embodiments, a primary winding may include a
conductive paint that has been painted on one or more outside
surfaces of the transformer core. In some embodiments, the
conductive sheet may include a metallic layer that has been
deposited on the transformer core using a deposition technique such
as thermal spray coating, vapor deposition, chemical vapor
deposition, ion beam deposition, plasma and thermal spray
deposition, etc. In some embodiments, the conductive sheet may
comprise a conductive tape material that is wrapped around the
transformer core. In some embodiments, the conductive sheet may
comprise a conductor that has been electroplated on the transformer
core. In some embodiments, a plurality of wires in parallel can be
used in place of the conductive sheet.
[0037] In some embodiments, an insulator may be disposed or
deposited between transformer core and the conductive sheet. The
insulator, for example, may include a polymer, a polyimide, epoxy,
etc.
[0038] The rectifier 135 may include any type of rectifier such as,
for example, a diode-based rectifier, a full-bridge rectifier
(e.g., as shown in FIG. 7), a half-bridge rectifier, a three-phase
rectifier, a voltage multiplying rectifier, etc. Any other type of
rectifier can be used.
[0039] The output filter 140 may include any type of filter. For
example, the output filter 140 may include a high pass filter, a
low pass filter, a band pass filter, etc.
[0040] Some embodiments may include a transformer resonant
converter 100 that has low stray inductance measured from the
primary side 160. Low stray inductance may include inductance less
than, for example, about 3,000 nH, 300 nH, 30 nH, 3 nH, etc.
[0041] Some embodiments may include a transformer resonant
converter 100 that has low stray capacitance as measured from the
primary side 160. Low stray capacitance may include capacitance
less than, for example, about 1,000 pF, 100 pF, 10 pF, etc.
[0042] Some embodiments may include the transformer resonant
converter 100 that can produce high average output power such as
greater than, for example, about 3 kW, 100 kW, 3 MW. For short
bursts the peak power output, for example, may exceed 30 kW, 300
kW, 3 MW. Some embodiments may include a transformer resonant
converter 100 that produces pulses with high voltage such as
greater than, for example, 5 kV, 25 kV, 250 kV, 2500 kV. Some
embodiments may include a transformer resonant converter 100 that
produces a high power burst operation with a peak power greater
than 5 times the average operating power of the converter. In some
embodiments, the peak power output may be in excess of the average
output power by a factor, for example, of 5, 50, 500.
[0043] In some embodiments, the transformer resonant converter 100
can produce high voltage pulses with a fast rise time, for example,
less than, for example, about 10 .mu.s, 1 .mu.s, 100 ns, 10 ns,
etc. for voltages greater than for example 5 kV, 30 kV, 100 kV, 500
kV, etc.
[0044] In some embodiments, the transformer resonant converter 100
can produce an output pulse with low voltage ripple such as, for
example, less than about 5%. Typical output voltage ripple may be
less than, for example, 15% or 0.5%.
[0045] In some embodiments, the transformer resonant converter 100
can operate with pulse width modulation that may allow for greater
control of the output waveform and/or allow for high efficiency
power output. In some embodiments, the transformer resonant
converter may include real time feedback and control of the high
voltage and/or power output. In some embodiments, the low stray
inductance and/or low stray capacitance, and/or high frequency of
operation can allow for this feedback loop to be fast.
[0046] In some embodiments, the transformer resonant converter 100
may significantly increase the overall power density of a system.
For example, the transformer resonant converter 100 could be used
with an electron tube driver for high-power radar systems and/or RF
systems. In some embodiments, the transformer resonant converter
100 may increase the overall power density of the high-power radar
systems and/or the RF systems. Power densities may exceed, for
example, 0.5 W/cm.sup.3, 5 W/cm.sup.3, 50 W/cm.sup.3, or 500
W/cm.sup.3.
[0047] In some embodiments, the transformer resonant converter 100
may include switching components that are at low voltage in a
standard H-bridge power supply configuration with a hard ground
reference. This may, for example, remove the requirement of
floating each module to high voltage as seen in the pulse step
modulator.
[0048] In some embodiments, a transformer resonant converter may
include high voltage components that include a high voltage
transformer and rectification diodes and other high voltage
components. These components can, for example, be packaged for safe
high voltage using oil, potting or other methods. In some
embodiments, some components may be in air with appropriate
stand-off to eliminate corona generation, arcing, and/or
tracking.
[0049] In some embodiments of the transformer resonant converter,
the output is transformer isolated, so the same system can provide
either a floating or ground referenced output and/or can be
configured to provide either a positive or negative polarity. This
may allow, for example, the same design to be utilized for any of
the various high voltage grids of a particular neutral beam
injection design including, for example, either positive or
negative ion extraction and acceleration as well as ion and
electron suppressor grids.
[0050] In some embodiments, a resonant converter may produce the
same power levels with a dramatic decrease in overall system size
and/or control complexity as compared to the pulse step modulators
used currently for smaller neutral beam injector systems.
[0051] In some embodiments, the resonant converter may be safe to
arc-faults due the inherent series resonant behavior of the supply.
The series resonant behavior of a resonant converter may have a
supply impedance that is matched to the load. When an arc occurs,
for example, this mismatch can reduce the power flowing in the
primary side 160 of the circuit and the voltage on the secondary
may fall, whereby the current in the arc cannot continue to
increase to the point of damage to the grids.
[0052] In some embodiments, the transformer resonant converter may
have very little energy stored in its output filter components. For
example, this stored energy may be less than, for example, about 10
J, 1.0 J, or 0.1 J. The high frequency of operation allows this
stored energy to be minimized. In some embodiments, minimizing this
stored energy can be important. This energy, for example, can
damage load components when arcs occur.
[0053] In some embodiments, a transformer resonant converter may be
modular. In some embodiments, a transformer resonant converter may
be easily scaled to higher output power levels making it a possible
choice for large neutral beam injector systems such as, for
example, like those used at NSTX, DIII-D, or ITER. For example,
power supplies with a transformer resonant converter can be added
together with output arranged in series to easily increase the
output voltage. Similarly, output current can be increased by
adding units in parallel on the primary as long as the high voltage
side is scaled to account for the increase current level.
[0054] FIG. 2 is a circuit diagram of a transformer resonant
converter 200 coupled with a load 250 according to some
embodiments. The transformer 225, for example, can have any number
of turns. For example, the transformer can have a turn ratio of
n=1, n=30, n=50, n=100, etc. The total series inductance is
represented by an inductor circuit element 205 (e.g., having an
inductance less than about 3,000 nH, 300 nH, 30 nH, 3 nH) on the
primary side 260, which may be primarily composed of the stray
inductance L.sub.s of the transformer. The total series capacitance
is represented by a capacitor circuit element 210 (e.g., having a
capacitance less than about 1,000 pF, 100 pF, 10 pF, etc.) on the
secondary side 265, which may be primarily composed of the stray
capacitance C.sub.s of the transformer. The stray inductance 205
and/or the stray capacitance 210 can be of any value depending on
the size, type, material, etc. of the transformer and/or the number
of turns of the transformer. In this circuit, a primary resistor
215 may be included in the circuit in series with the inductor 205
and/or the capacitor 210. In some embodiments, the primary resistor
215 may have a small value, such as, for example, less than 3,000
mOhms, 300 mOhms, 30 mOhms, 3 mOhms.
[0055] In this example, the transformer resonant converter 200
includes switching circuitry with four switch circuits 230.
However, any number of switch circuits can be used. Each switch
circuit 230 may include a solid-state switch 235 with any number of
circuit elements. The solid-state switch may include, for example,
an IGBT switch, MOSFET switch, FET switch, GaN switch, etc. Each
switch circuit 230 may also include stray inductance represented by
circuit element 240 and/or stray resistance represented by circuit
element 245. Each switch circuit 230 may also include a diode
255.
[0056] In this example, the secondary side of the transfer may also
include a full bridge rectifier 260, an output filter 270, a load
element 250 (e.g., in a specific example, comprising an 86 k Ohm
resistor), and/or a filter resistor 280 (e.g., in a specific
example, comprising a 10 k Ohm resistor) that acts in conjunction
with an external user load capacitor 285 (e.g., in a specific
example, comprising a capacitor of 30 pF). In the circuit shown,
for example, no feedback and control regulation may be
required.
[0057] Any number of circuit elements combined in any configuration
may follow the rectifier. For example, these other elements may
include capacitive, inductive, and/or resistive filter components,
and/or the external loads.
[0058] In some embodiments, a transformer resonant converter (e.g.,
transformer resonant converter 100, transformer resonant converter
200, transformer resonant converter 700, etc.) can produce pulses
with various properties. For example, a transformer resonant
converter can produce pulses with a voltage greater than about 30
kV. For example, a transformer resonant converter can produce
pulses with a voltage greater than about 5 kV, 25 kV, 250 kV, or
2,500 kV. For example, a transformer resonant converter can produce
pulses with a rise time to or a fall time from voltages greater
than about 25 kV of less than about 300 .mu.s, 30 .mu.s, 3 .mu.s.
For example, a transformer resonant converter can produce pulses
with a variable pulse width. For example, a transformer resonant
converter can produce pulses with a variable frequency. For
example, a transformer resonant converter can produce pulses with a
variable voltage. For example, a transformer resonant converter can
produce pulses for a dielectric barrier discharge and/or neutral
beam injection devices. For example, a transformer resonant
converter can produce pulses that have a pulse width of any
duration such as, for example, ranging from about 1 .mu.s to
DC.
[0059] For example, a transformer resonant converter can produce
pulses with a pulse repetition rate greater than about 1 kHz for
continuous operation at average power levels in excess of several
kilowatts. For example, a transformer resonant converter can
produce pulses having a pulse repetition frequency greater than
about 1 kHz, 30 kHz, or 1000 kHz. For example, a transformer
resonant converter can produce pulses having power greater than
about 3 kW, 100 kW, or 3 MW.
[0060] In some embodiments, a transformer resonant converter can be
housed in a rack-mountable enclosure (e.g., standard 6U enclosure
that is has approximate dimensions of 10''.times.17''.times.28'').
In some embodiments, a transformer resonant converter may have a
high power density, for example, a power density that can exceed
0.5 W/cm.sup.3, 5 W/cm.sup.3, 50 W/cm.sup.3 or 500 W/cm.sup.3.
[0061] In some embodiments, a transformer resonant converter may
include any type of solid state switches such as, for example, an
IGBT, an FET, a MOSFET, a SiC junction transistor, a GaN switch,
etc.
[0062] FIG. 3 is a photograph of an example transformer resonant
converter including a transformer with windings 310 and a plurality
of resistors 305. The value of the cumulative resistance of the
plurality of resistors 305 can be determined from equation 2 for a
give Q factor. The transformer resonant converter also includes a
plurality of solid state switches 315 that are coupled with heat
sinks. The solid-state switches can be arranged, for example, in
the full bridge topology in this instance. The transformer resonant
converter also includes a plurality of full-bridge rectifying
diodes 320. Numerous other circuit elements can also be
included.
[0063] FIG. 4 is an example waveform created from a transformer
resonant converter according to some embodiments. In this example,
the output voltage is greater than 30 kV, has a rise time of about
4 .mu.s and a flat top width of about 12 .mu.s.
[0064] FIG. 5 is another example waveform created from a
transformer resonant converter according to some embodiments. This
waveform was produced by the switching resonant converter shown in
FIG. 2. In this example, the input voltage to the transformer
resonant converter was 600 V and the output pulse is 30 kV. In this
example, the rise time is about 5 .mu.s and the flat top width is
about 20 .mu.s. These waveforms could have additional rises, flat
tops, and falls, depending on the modulation of the resonant
converter. This waveform shows one typical output pulse; various
other output pulses are possible. In some embodiments, the high
power density, power, frequency, rise time, and/or voltage of the
output of a transformer resonant converter can be unique. These
attributes, for example, may be enabled by the use of a transformer
(and/or circuit) with low stray capacitance and/or low stray
inductance that allows for operation at high frequency, and the use
of solid state switches that operate at high power with very fast
transition times.
[0065] FIG. 7 is a circuit diagram of an example transformer
resonant converter 700 according to some embodiments. In this
example, a transformer 705 is coupled with and/or is part of a
resonant converter topology where the transformer 705 has a step-up
voltage of n, which represents the ratio of turns of the primary
winding to the turns of the secondary winding of the transformer
705. In this transformer, the stray inductance L.sub.s is
represented by inductor 715, and/or the stray capacitance C.sub.s
is represented by capacitor 720 of the transformer. These stray
elements are leveraged as part of the resonant converter 700. The
stray inductance L.sub.so and stray capacitance c.sub.so of other
circuit elements can also be leveraged be used in conjunction with
stray inductance L.sub.s 715 and capacitance C.sub.s 720 to achieve
the desired resonant frequency f, and Q. Resistor 710 represents
the additional resistance R.sub.a that may be included on the
primary side of the transformer. Once the stray inductance L.sub.s
and the stray capacitance C.sub.s of the transformer are known, and
the total inductance and capacitance are known, even if they are
only comprised of stray elements, the resistance, for example,
R.sub.pri, can be selected to produce a given Q factor using, for
example, equation (2). In this example, the voltage on the
secondary of the transformer can be calculated from the
following:
V.sub.out=QnV.sub.c (3).
Thus, the voltage on the secondary of the transformer can be
stepped up by the transformer by a factor of n multiplied by the
resonant converter by a factor of Q.
[0066] In some transformer resonant converters, the total stray
inductance and the total stray capacitance, of the transformer
and/or other circuit elements are kept low, for example, to produce
a resonant oscillating voltage at high frequency, and an output
voltage with fast rise times and/or fast fall rise times. For
example, the circuit can switch at high frequencies such as, for
example, at frequencies greater than 50 kHz, 500 kHz, 5 MHz, for
example. The low total stray inductance and the low total stray
capacitance of the transformer and/or other circuit elements may
also, for example, be kept low to produce fast rectified rise
times, faster than 100 .mu.s, 10 .mu.s, 1 .mu.s, for example.
[0067] In some embodiments, the stray capacitance can be measured
from the secondary side of the transformer. Alternatively, the
stray capacitance can be measured from the primary side of the
transformer, which is equal to the capacitance on the secondary
side of the transformer times the square of the turns ratio n.
[0068] In some embodiments, the stray inductance can be measured
from the primary side of the transformer. Alternatively, the stray
inductance can be measured from the secondary side of the
transformer, which is equal to the inductance on the primary side
of the transformer times the square of the turns ratio n.
[0069] In some embodiments, the total equivalent series capacitance
can be measured from the secondary side of the transformer.
Alternatively, the total equivalent series capacitance can be
measured from the primary side of the transformer, which is equal
to the total equivalent series capacitance on the secondary side of
the transformer times the square of the turns ratio n.
[0070] In some embodiments, the total equivalent series inductance
can be measured from the primary side of the transformer.
Alternatively, the total equivalent series inductance can be
measured from the secondary side of the transformer, which is equal
to the total equivalent series inductance on the primary side of
the transformer times the square of the turns ratio n.
[0071] The term "substantially" means within 5% to 15% of the value
referred to, or within manufacturing tolerances.
[0072] Numerous specific details are set forth herein to provide a
thorough understanding of the claimed subject matter. However,
those skilled in the art will understand that the claimed subject
matter may be practiced without these specific details. In other
instances, methods, apparatuses, or systems that would be known by
one of ordinary skill have not been described in detail so as not
to obscure claimed subject matter.
[0073] The use of "adapted to" or "configured to" herein is meant
as open and inclusive language that does not foreclose devices
adapted to or configured to perform additional tasks or steps.
Additionally, the use of "based on" is meant to be open and
inclusive, in that a process, step, calculation, or other action
"based on" one or more recited conditions or values may, in
practice, be based on additional conditions or values beyond those
recited. Headings, lists, and numbering included herein are for
ease of explanation only and are not meant to be limiting.
[0074] While the present subject matter has been described in
detail with respect to specific embodiments thereof, it will be
appreciated that those skilled in the art, upon attaining an
understanding of the foregoing, may readily produce alterations to,
variations of, and equivalents to such embodiments. Accordingly, it
should be understood that the present disclosure has been presented
for-purposes of example rather than limitation, and does not
preclude inclusion of such modifications, variations, and/or
additions to the present subject matter as would be readily
apparent to one of ordinary skill in the art.
* * * * *